@agleue, @SusanNiemeyer, @kmoore2431, an @pashultz ...
There was a known issue that Instructure (the folks that make Canvas) was recently made aware of with respect to the bottom scroll bar in Grades. Please see this Known Issue document for more details:
Gradebook scrollbar is cutting off the last row of... - Instructure Community - 601863 (canvaslms.co...
I'm not sure if the recent fix has caused another issue or not.
If things are still not working correctly for you, first try clearing your browser's cache/temp files, closing the browser, and then re-starting the browser to see if things have corrected themselves.
If this doesn't work, then reach out to Canvas Technical Support:
How do I get help with Canvas as an instructor?
I hope this will be helpful for you.